Silicone hydrogels are important contact lens materials for promoting corneal health by enabling higher oxygen permeability. They, however, suffer from the drawback of having higher lipid deposition than conventional hydrogels which can negatively affect clarity and end of day comfort. A polymerizable zwitterionic silicone (ZiSi) monomer was incorporated into silicone hydrogel formulations to improve wettability and minimize the hydrophobic domains with the intent of reducing lipid adsorption. The effect of this zwitterionic silicone monomer in silicone hydrogel formulations on clarity, oxygen permeability, equilibrium water content and size of hydrophobic domains was investigated.

Silicone hydrogel films made with zwitterionic silicone monomer have comparable oxygen permeability (Dk) and equilibrium water content (EWC) while maintaining clarity and mechanical stability to control films. The addition of zwitterionic silicone monomer to the silicone hydrogel formulation did not seem to have a detrimental effect on the silicone hydrogel properties, while resisting any significant dye staining by the lipophilic dye used in this study.